RU2692159C1 - Verification method and method of electric storage device production - Google Patents

Abstract

FIELD: electricity.SUBSTANCE: invention relates to a method of checking an electrical accumulator device, which includes: designing a circuit with a charged electric storage device and a power source and passing current through a power source to the circuit in the charging or discharging direction of the electric storage device; and when current passes, determination of quality of electric accumulator device based on convergence condition of passing current. When current flows, output voltage of power source changes from initial value at passage of time.EFFECT: fast determination of quality of electric storage device irrespective of changes in different conditions.11 cl, 9 dwg

Description

Technical field

The present invention relates to a verification method for determining the quality of an electrical storage device. The present invention also relates to a method for producing an electrical storage device, the method including a method for testing an electrical storage device as one of the steps.

The level of technology

Traditionally, many testing methods have been proposed to determine the quality of batteries and other electrical storage devices. For example, in Japanese Patent Application Publication No. 2010-153275, a holding step for holding a battery, i.e. the determination target, in the overpressure state, is fulfilled, and the battery voltage is measured before and after the holding step. The difference in battery voltage before and after the holding step is just the magnitude of the voltage drop caused by the hold. A battery that has a large voltage drop indicates that the battery has a large amount of self-discharge. Accordingly, the quality of the battery can be determined based on the size of the magnitude of the voltage drop. This verification method can be performed as one production method.

Summary of Invention

However, the traditional definition of battery quality has the following problems. So, the definition of quality takes time. The reason why the definition of quality takes time is that a long holding time is necessary during the holding step in order to obtain a voltage drop large enough to be meaningful. This may be inherent in contact resistance when measuring voltage. To measure voltage, the meter connects between the two terminals of the battery. At this time, the contact resistance is inevitably created between the battery terminals and the terminals of the measuring tool, so that the contact result influences the measurement result. Whenever the battery terminals and the terminals of the measuring instrument are connected, a different contact resistance is created. Accordingly, as long as the voltage drop itself is not large enough, the change in contact resistance between the respective measurements cannot be ignored.

In addition, the accuracy of the voltage measurement itself is not very high. This is due to the fact that the voltage measurement is inevitably influenced by the voltage drop in the path of the electric current during the measurement. In addition, the contact points between the terminals on the battery side and the terminals on the meter side differ to some extent each time the connection code is made. Therefore, the level of the voltage drop also changes each time the voltage measurement is performed. Accordingly, it may be convenient to reduce the measurement time of the self-discharge value and thereby improve the measurement accuracy by measuring the current instead of measuring the voltage. Unlike the voltage measurement, the current measurement is almost not affected by the place of contact, since the electric current is constant throughout the circuit. However, a simple replacement of a voltage measurement with a current measurement does not provide a successful determination. This is because the measurement result depends on fluctuations in various conditions, such as battery charge voltage and measurement environment.

The present invention provides a verification method and a production method for an electrical storage device that performs a rapid determination of the quality of an electrical storage device regardless of changes in conditions.

A method for testing an electrical storage device in a first aspect of the present invention includes: drawing up a circuit with a rechargeable electric storage device and a power source, and passing a current power source into the circuit in the direction of charging the electric storage device or in the discharge direction of the electric storage device changes from the original value with the passage of time; and, when passing a current, determining the quality of the electrical storage device based on the state of convergence of the current passing through the circuit.

In the method for checking an electrical storage device in the above aspect, the quality of the electrical storage device is determined by measuring a current passing through a circuit including an electrical storage device and a power source. That is, a change in the circuit current caused by a voltage drop based on self-discharge of the electrical storage device is used as a determination criterion. Since the current measurement can be performed with a higher accuracy than the voltage measurement, a more adequate determination can be performed in a shorter time. Here, the change in the output voltage of the power source from the initial value with the passage of time accelerates the time of convergence of the circuit current and achieves a further reduction in the detection time.

The first aspect may include setting the initial value to a voltage value before starting to test a rechargeable electrical storage device. When current is passed, the output voltage after the start of the test can be changed so that the output voltage increases so that the increase limit of the output voltage increases when the current increase after the start of the test becomes larger, and when determining the quality of the electrical storage device, the quality of the electrical storage device can be determined based on the time required until the current converges. Thus, the manifestation of the reaction of the current circuit to the limit of increasing the output voltage of the power source can further accelerate the time of convergence of the current circuit.

In the first aspect, when the circuit current reacts to the output voltage of the power source, the output voltage can be calculated using a constant, which is the product of the parasitic resistance of the circuit and a predetermined positive factor, which is less than one, as the sum of the voltage of the electrical storage device circuit current and constant values. Thus, the increase limit of the output voltage of the power source can be easily calculated using a known value, and the output voltage of the power source can be increased.

In the first aspect, when the circuit current reacts to the output voltage of the power source, the output voltage can be calculated using the virtual resistance value, as the sum of the voltage of the electrical storage device and the product of the circuit current value and the sum of the parasitic resistance of the circuit and the virtual resistance value, virtual resistance is used when the increase in output voltage is replaced by a model, where the absolute value of the virtual resistance, which is a virtual resistance having a negative or zero resistance value, increases, instead of the output voltage, which is set constant. Also with this configuration, the limit of increase in the output voltage of the power source can be appropriately calculated, and the output voltage of the power source can be increased.

The first aspect may include: before drawing up the circuit, obtaining the voltage value before starting to check the rechargeable electrical storage device; before passing the current, matching the output voltage with the voltage value; and determining the initial output voltage of the power source by passing the current by adjusting the output voltage so that the current passing through the circuit in the state, after the output voltage coincides with the voltage value, is suppressed.

The state of the change in the circuit current after the start of the test is greatly affected by the accuracy of the output voltage setting of the power source at the time the test starts. When the initial output voltage of the power source is higher than the initial voltage of the electrical storage device, a surge may occur at which the circuit current exceeds the convergence value. Meanwhile, when the initial output voltage of the power source is lower than the initial voltage of the electrical storage device, the direction of current flow is temporarily reversed, and then the convergence value is reached. In any case, the moment of convergence of the current is significantly delayed. Accordingly, fine tuning the initial output voltage of the power source as in the current aspect can ensure that the current of the circuit converges early.

In the first aspect, when passing a current, the voltage of the power source at the beginning of the test can be set to the value obtained by adding the product of the initial self-discharge current of the electrical accumulation of the device without a defect and the parasitic resistance of the circuit with the voltage of the electrical storage device storage device can be determined based on whether or not the increase in current is after the start of the test. and at a predetermined level.

Thus, setting the initial output voltage of the power source to a voltage higher than the initial voltage of the electrical storage device makes it possible to set the circuit current so that the self-discharge current of the non-defective device is suppressed. Accordingly, the self-discharge of the electrical storage device after the start of the test can be practically adjusted to zero. Therefore, verification can only be performed based on whether there is a significant increase in circuit current after the start of the test. This makes it possible to test the electrical storage device in a shorter time.

In the method of checking the electrical storage device in terms of determining quality based on the time of convergence of the circuit current, the voltage of the power source at the beginning of the test can be set to the value obtained by adding the product of the initial self-discharge current of the electrical storage device without a defect and the parasitic resistance of the circuit determined by the passage of current. This is because the initial output voltage of the power source higher than the initial voltage of the electrical storage device also results in an additional decrease in the time of convergence of the circuit current.

The first aspect may include measuring the voltage value before testing a rechargeable electrical storage device in which the measurement of the voltage value and passing current can be performed under conditions where the electrical storage device has a constant temperature. When the temperature of the electrical storage device changes in the middle of the test, the voltage of the electrical storage device and the current of the circuit are also affected by the change. Accordingly, the determination of convergence and an increase in the current of the circuit can also be influenced. In the present aspect, such an effect can be eliminated by setting the temperature of the electrical storage device to be constant, which allows for an appropriate determination regarding convergence or increase in circuit current.

The first aspect, which performs the voltage measurement step, may further include, before measuring the voltage value, and in the middle of measuring the voltage value and current flow, repeatedly obtaining the temperature in parallel with measuring the voltage value and passing the current, and continuing to measure the voltage value and current passing, when the fluctuation of the resulting temperature is in a predetermined acceptable range of oscillation. With such a configuration, only when the temperature fluctuation in the electrical storage device is within the acceptable oscillation range, the measurement of the voltage value and the current transmission can be laid.

The first aspect may include measuring the voltage value before testing a rechargeable electrical storage device in which the electrical storage device may have a flat square shape, and measuring the voltage value and passing current can be performed provided that the electrical storage device is under pressure the direction of the thickness of the electrical storage device. In such a state of increased pressure, the influence of metallic foreign matter, which can be introduced between the electrode plates of the electrical storage device, is manifested. Consequently, checking in such a situation provides an opportunity for more proper checking of the electrical storage device.

A method for producing an electrical storage device in the second aspect of the present invention includes: performing an initial charge of an assembled and uncharged electrical storage device to a predetermined state of charge to provide a charged electrical storage device; and checking a rechargeable electrical storage device by the inspection method according to any method of the first aspect. This makes it possible to reduce the time required for the verification phase, which is the process of the production process.

With this configuration, a verification method and a production method of an electrical storage device are provided that achieve a quick determination of the quality of the electrical storage device regardless of changes in conditions.

Brief Description of the Drawings

Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numbers designate like elements, and on which:

FIG. 1 is a circuit diagram illustrating the configuration of a circuit assembled to perform a test method of a battery in an embodiment;

FIG. 2 is an external view illustrating an example of a battery to be tested in an embodiment;

FIG. 3 is a graph view illustrating a time-dependent change in voltage and current according to the basic principle of the test;

FIG. 4 is a graph view illustrating an example of a change in circuit current when the output voltage is constant.

FIG. 5 is a graph view illustrating an example of a change in circuit current as the output voltage increases;

FIG. 6 is a schematic view illustrating a situation where a plurality of batteries to be tested are bundled together with a separator by means of a connecting element in an embodiment;

FIG. 7 is a circuit diagram in which virtual resistance is introduced;

FIG. 8 is a graph view illustrating the difference in the state of convergence of the circuit current due to the height of the initial output voltage; and

FIG. 9 is a graph view illustrating an example of a change in circuit current when the initial output voltage is set higher than the initial battery voltage.

Detailed description of embodiments of the invention.

Hereinafter, embodiments that will implement the present invention are described in detail with reference to the accompanying drawings. As illustrated in FIG. 1, the test method of the electrical storage device in the present embodiment is performed in a state where the battery 1, which is an electrical storage device to be tested, is connected to the measurement device 2 to assemble the circuit 3. First, the basic principle of the test method will be described battery 1 using a measuring device 2.

The basic principle

The battery 1, which is schematically illustrated in FIG. 1 has an actual appearance in a flat square shape, as illustrated in FIG. 2, for example. The battery 1 in FIG. 2 is made of an electrode laminate 20 placed in the outer housing 10. The electrode laminate material 20 is a laminate of a positive electrode plate and a negative electrode plate with a separator provided between them. The outer case 10 accommodates an electrolytic solution in addition to the electrode laminate 20. The rechargeable battery 1 has positive and negative terminals 50, 60 provided on its outer surface. Without limiting the square shape, as in FIG. 2, the battery 1 may have other shapes, such as a cylindrical shape.

A further description will be provided for FIG. 1. In FIG. 1 schematically illustrates rechargeable battery 1. Rechargeable battery 1 in FIG. 1 is expressed as a model that includes the electromotive element E, the internal resistance Rs and the resistance Rp of a short-circuited circuit. The internal resistance Rs is placed in series with the electromotive element E. The short-circuit resistance Rp simulates an electrically conductive path provided by the smallest metallic foreign substance that can penetrate the electrode multilayer material 20. The short-circuit resistance Rp is placed parallel to the electromotive element E.

Measuring device 2 has a DC power source 4, an ammeter 5, a voltmeter 6 and probes 7, 8. Ammeter 5 is placed in series with the DC power source 4, while the voltmeter 6 is parallel with the DC power source 4. The DC power source 4 has an AC output voltage VS. The DC power source 4 is used to apply the output voltage VS to the battery 1, as described later. Ammeter 5 measures the current passing through circuit 3. Voltmeter 6 measures the voltage between the probes 7, 8. Probes 7, 8 of the measuring device 2 are connected to terminals 50, 60 of the battery 1 to form circuit 3 in FIG. one.

Chain 3 in FIG. 1 additionally has a parasitic resistance Rx. The parasitic resistance Rx includes the contact resistance between the probes 7, 8 and terminals 50, 60 in addition to the resistance of the conductive conductor of each piece of measuring device 2. Although the parasitic resistance Rx is illustrated as if it exists only in the conductive conductor on the probe side 7 FIG. 1, it is just for the convenience of graphic illustration. The stray resistance Rx is present throughout chain 3 in reality.

In the verification method using the measuring device 2, the size of the self-discharge value of the battery 1 is checked. When the self-discharge value is large, the battery 1 is defective, while when the self-discharge value is small, the battery 1 is non-defective. Accordingly, first, the battery 1 is charged before the battery 1 is connected to the circuit 3. Then, the charged battery 1 is connected to the chain 3, and in this state, the self-discharge value of the battery 1 is calculated using the measuring device 2. Based on the result of the calculations determines the quality of the battery 1.

In particular, the charged battery 1 is connected to chain 3. In this case, the charged battery 1 is connected to chain 3 after the high temperature hold, which is usually performed after charging, is completed and the battery voltage becomes stable. However, the verification of this embodiment itself is carried out at room temperature. The voltage VB of the battery in battery 1 is measured after charging and holding at high temperature. The measured value is the original battery voltage VB1. Further, the output voltage VS of the measuring device 2 is adjusted to match the original battery voltage VB1. The battery 1 is then connected to the circuit 3. The output voltage VS at this time coincides with the initial voltage VB1 of the battery of the battery 1.

In this state, the output voltage VS coincides with the original battery voltage VB1, with the output voltage direction VS being opposite to the voltage direction VB of the battery 1. Accordingly, the VS, VB voltages neutralize each other, resulting in the circuit current IB for chain 3 becomes zero. The output voltage VS of the measuring device 2 is kept in a state of keeping constant in the original battery voltage VB1.

The subsequent state of chain 3 is illustrated in FIG. 3. In FIG. 3, the horizontal axis represents time, and the vertical axis represents voltage (left side) and current (right side). Regarding the time expressed by the horizontal axis, the time T1 on the left edge in FIG. 3 represents the beginning of the application of the output voltage VS, which is equal to the original battery voltage VB1, as described above. After time T1, the battery voltage VB gradually decreases from the original battery voltage VB due to self-discharge of the battery 1. As a result, the balance between the output voltage VS and the battery voltage VB is disturbed, resulting in a circuit current IB flowing into circuit 3. The circuit current IB gradually increases from zero The current IB of the circuit is directly measured by an ammeter 5. At time T2 after time T1, the battery voltage VB and the increase in current IB of the circuit both become saturated, and from that time both the battery voltage VB and the circuit current IB become constant (VB2, IBs).

As is clear from FIG. 3, an increase in circuit current IB and a battery voltage drop VB are both steeper in a defective battery 1 than in a non-defective battery 1. Accordingly, the circuit current IBs after convergence in case of a defective battery 1 is greater than circuit current IBs after convergence non-defective battery 1. The battery voltage VB2 of the defective battery 1 after converging below the battery voltage VB2 of the non-defective battery 1 after converging.

The reason why the state of circuit 3 is as illustrated in FIG. 3 after time T1. First, the battery voltage VB drops due to self-discharge of the battery 1, as previously described. Due to self-discharge, the current ID of the self-discharge passes to the electromotive cell E of the battery 1. The current ID of the self-discharge becomes larger when the self-discharge value of the battery 1 becomes larger. The self-discharge current ID becomes smaller when the self-discharge value of the battery 1 becomes smaller. The battery 1, in which the above-mentioned closed-loop voltage Rp is small, tends to have an increased self-discharge current ID.

Meanwhile, the circuit current IB, which runs due to the battery voltage VB after time T1, is the current flowing in the direction of charge of the battery 1. That is, the circuit current IB acts in the direction of suppressing the self-discharge of the battery 1 and runs in the direction opposite to the current ID of the self-discharge in the battery 1. When the current IB of the circuit increases to the same level as the current ID of the self-discharge, self-discharge practically stops. This happens during T2. Therefore, after time T2, both the battery voltage VB and the circuit current IB become constant (VB2, IBs). Whether or not the current of an IB circuit has converged can be determined in a known manner. For example, the value of the current IB of the circuit can be sampled at an appropriate frequency, and when the change in value becomes less than a predetermined reference value, it can be determined that the current IB of the circuit has converged.

As previously stated, the IB circuit current can be directly obtained as the value of the meter indicator 5. Accordingly, the quality of the battery 1 can be determined by setting the reference value IK for the circuit current IBs after convergence. When the current IBs of the circuit after convergence is greater than the control value IK, it can be determined that the battery 1 is defective with a large amount of self-discharge. When the circuit current IBs is less than the IK test value, it can be determined that the battery 1 is non-defective with a small amount of self-discharge.

The processing time (from time T1 to time T2) required in this verification method is shorter than the retention time in the method described in the section "prior art". Since the method involves measuring the current, the determination accuracy is high. The quality of determination using the battery voltage VB2 after convergence described in FIG. 3, is not a very good tool. This is because the battery voltage VB is not necessarily represented as the correct value of the voltmeter 6 indicator. This is the end of the description relating to the basic principle of the method for testing the battery 1 using the measuring device 2. When producing the battery 1, the initial charge phase to perform the initial charge uncharged battery 1 to a predetermined charged state to provide a charged battery 1 by it, and a step of checking to verify the charged battery 1 can be performed. During the verification phase, the aforementioned verification method can be performed.

Characteristic moment 1 in the present embodiment: Increasing the output voltage VS

It has been described so far that the output voltage VS of the measuring device 2 is constant. However, VS output voltage may not be constant. Rather, the processing time required for the determination can be further reduced by properly changing the output voltage VS. This point will be described later.

Referring to FIG. 4 and 5, the advantages of varying the output voltage VS will be described. FIG. 4 is one example of the transition state of an actual circuit current IB when the output voltage VS is constant, as previously described. In the example of FIG. 4, the VS output voltage is constant from the initial set point, and the convergence of the circuit current IB takes approximately 1.5 days (time T2). The example in FIG. 4 is an example of measurement in a state where a plurality of batteries 1 are bundled in a pack 100 together with a separator 160 by means of a coupling element 130, as illustrated in FIG. 6, under the conditions outlined below. The batteries 1 in the stack 100 are each in a state of increased pressure in the direction of their thickness.

- Battery capacity: 4 Ah

- Positive electrode active material: a three-component lithium-containing compound

- Active material of the negative electrode: graphite

- Ambient temperature: 25 ° C

- Binding load: 1 MPa

While the measurement time is 1.5 days, in FIG. 4 is sufficiently shorter than the measurement time in the case where the determination is made based on the voltage measurement, the processing time may additionally be shortened by changing the output voltage VS. FIG. 5 illustrates an example of further reduction in processing time. In the example of FIG. 5 VS output voltage increases and converges only within 0.1 day. In the example of FIG. 5, the above measurement conditions are themselves the same as those in FIG. 4. However, since the rechargeable batteries 1 to be measured are individually different, the initial value of the output voltage VS and the current IB (IBs) of the circuit after convergence do not coincide with the values in FIG. 4. In the example of measurement in FIG. 5, a non-defective rechargeable battery 1 is used. The current IB (IBs) of the circuit after convergence becomes greater when a defective rechargeable battery 1 is used instead.

Additionally, a description is given of the case of increasing the output voltage VS, as in FIG. 5. First, the circuit current IB in circuit 3 in FIG. 1 is provided by the following expression (1) with the output voltage VS of the measuring device 2, the battery voltage VB and the parasitic resistance Rx:

IB = (VS - VB) / Rx (1)

When the output voltage VS is constant, the circuit current IB increases, as mentioned earlier, due to the battery voltage VB caused by self-discharge of the battery 1. When the circuit current IB increases to a level equal to the self-discharge current ID, the discharge of the battery 1 almost stops. As a result, both the battery voltage VB and the circuit current IB from this time become constant (VB2, IBs), as previously described. That is, the circuit current IBs after convergence indicates the self-discharge current ID of the electromotive cell E of the battery 1.

In the case of increasing the output voltage VS, the expression (1) is similarly set. However, the degree of increase in the IB circuit current is higher by increasing the output voltage VS than the degree of increase in the case where the output voltage VS is constant. Accordingly, the time required until the current IB of the circuit becomes equal to the current ID of the self-discharge is reduced. This is the reason why the IB circuit current converges early, as mentioned above. However, if the VS output voltage increases blindly, there is a chance that the VS output voltage may become too high. If the VS output voltage is too high, the circuit current IB does not converge properly, resulting in a failure to determine. Therefore, it is necessary to limit the level of increase in the output voltage VS. In particular, in the present embodiment, the output voltage VS increases in a range that makes it look similar to the parasitic resistance Rx becoming small in expression (1). When the parasitic resistance Rx becomes small, the current IB of the circuit increases proportionally.

Accordingly, in the present embodiment, the concept of virtual resistance Rim is introduced, as illustrated in FIG. 7. Virtual resistance Rim is a virtual resistance with a negative resistance value or a resistance value equal to zero. In the circuit diagram in FIG. 7 virtual resistance Rim is introduced in series with the parasitic resistance Rx. Although such resistance is not present in reality, the situation when the output voltage VS increases, is considered by replacing the situation with the model, when the absolute value for the resistance value for the virtual resistance Rim increases instead of the output voltage VS, which is set as constant. However, the sum of the parasitic resistance Rx and the virtual resistance Rim must be positive, despite the fact that they decrease. Hereinafter, the sum of the parasitic resistance Rx and the virtual resistance Rim is called the pseudoparasitic resistance Ry. The circuit current in the model where pseudoparasitic resistance Ry is introduced is expressed as in the following expression (2).

IB = (VS - VB) / (Rx + Rim) (2)

Here, suppose that the parasitic resistance Rx is 5 ohms. In this case, the IB circuit current, when the virtual resistance Rim is 0 Ohms, is different from the IB circuit current, when the virtual resistance Rim is -4 Ohms. That is, according to expression (2), the IB current in the case of -4 Ω (equivalent to the resistance after the start of measurement) is five times the current IB of the circuit in the case of 0 Ω (equivalent to the resistance at the beginning of the measurement). This is due to the fact that the pseudoparasitic resistance Ry (= Rx + Rim) decreases to 1/5 for the case when the virtual resistance Rim is 0 Ω.

The above expression (2) can be changed into the following expression (3):

VS = VB + (Rx + Rim) * IB (3)

Expression (3) expresses that the output voltage VS is obtained by adding the product of the pseudoparasitic resistance Ry and the current IB of the circuit with the battery voltage VB. Since the virtual resistance Rim in the pseudoparasitic resistance Ry is not present in reality, as described earlier, expression (3) is established by increasing the output voltage VS to the voltage obtained by adding the product of the parasitic resistance Rx and the current IB of the circuit with battery voltage VB. That is, the value obtained by dividing the output voltage increment VS by the circuit current IB corresponds to the absolute value of the virtual resistance Rim.

In the case where the measurement starts after the voltage VS coincides with the original battery voltage VB1, as described above, the output voltage VS increases in accordance with the circuit current IB during time, based on expression (3), with the proper frequency. The frequency of increasing the output voltage VS is approximately one per second, for example. The frequency may not be constant. Therefore, the increase limit in the output voltage VS becomes larger when the increase in circuit current IB after the start of the test becomes larger. When the increase in current IB of the circuit converges, the increase in output voltage VS also converges. As a consequence, a measurement can be implemented, as in FIG. five.

The increase limit in the output voltage VS, corresponding to the increment of the IB current, is the product of the parasitic resistance Rx and the IB current, as described above. That is, when the limit of increase in the output voltage VS is expressed as ΔVS, the limit of increase of ΔVS is represented by the following expression (4):

ΔVS = Rx * IB (4)

However, without limiting the aforementioned value, the zoom limit can be a value obtained by multiplying the product from expression (4) by a positive coefficient K, which is less than one. The specific value of the coefficient K may be any value in the above range and may be set in advance. That is, the limit of increasing ΔVS can be calculated by the following expression (5):

ΔVS = K * Rx * IB (5)

The product of the coefficient K and the parasitic resistance Rx can be obtained as a constant M in advance, and the limit ΔVS of the output voltage VS can be calculated by multiplying the circuit current IB by a constant M. (6):

VS = VB + M * IB (6)

From the point of view of the early convergence of the increase in the current IB circuit, the most effective is to use, as the limit of the increase in the output voltage VS, the product from the expression (4) as it is. However, in this case, there may be a situation where the above-mentioned pseudoparasitic resistance Ry becomes a value with a minus sign due to the accuracy of the value of the parasitic resistance Rx and for other reasons. If this situation occurs, the change in the IB circuit current diverges, making it difficult to perform the required measurement. Accordingly, multiplying by a factor, as mentioned above, can avoid the risk of divergence.

Here, in order to actually perform the measurement in this control, it is necessary to obtain the value of the parasitic resistance Rx. In the parasitic resistance Rx, the proportion of the aforementioned contact resistance between the probes 7, 8 and terminals 50, 60 is different each time circuit 3 is assembled. However, the parasitic resistance Rx, including the contact resistance, can be measured as described below, for example. That is, the value of the indicator of a voltmeter 6 is measured in two states, when, in FIG. 1, the output voltage VS of the DC power source 4 is turned off, and both terminals of the measuring device 2 are connected through an appropriate resistance, and when the connection is disconnected. Consequently, the parasitic resistance Rx can be calculated based on the resistance value for the corresponding resistance and two voltmeter 6 values. Depending on the required measurement accuracy, it may be unnecessary to take into account the contact resistance, which differs each time. In this case, the preset fixed value can be used as the parasitic resistance Rx.

Thus, the VS output voltage increases, while the IB current value of the circuit responds to the VS output voltage. As a consequence, an increase in the current of the IB circuit may converge early. Thus, the processing time required for the determination can be further shortened.

Characteristic moment 2 in the present embodiment: Fine tuning the initial output voltage of the VSI

A description is now provided of fine tuning the initial value (initial output voltage) of the output voltage VSI. In the above description, when the battery 1 is connected to circuit 3, the output voltage VS is adjusted to make the output voltage VS the same as the original battery voltage VB1 of battery 1. When the tuning accuracy of the initial output voltage VSI is poor, the convergence of circuit current IB may take . This moment will be described first.

FIG. 8 illustrates three patterns of magnification in an IB circuit current after the start of the test. These magnification patterns, as long as the circuit current IB does not converge, are present due to the accuracy of setting the initial output voltage VSI. Patterns A, B, C in FIG. 8 appear in the following cases, respectively.

Pattern A: The initial output voltage of the VSI is slightly higher than the initial voltage of the VB1 battery.

Pattern B: The initial output voltage of the VSI coincides well with the initial voltage of the VB1 battery.

Pattern C: The initial output voltage of the VSI is slightly lower than the initial voltage of the VB1 battery.

Although the final convergence value of the IB circuit current is approximately 20 μA in FIG. 8, the three patterns have the following characteristics in the process of achieving the final convergence, respectively.

Pattern A: The electric current value temporarily exceeds the convergence value (about 2000-3000 seconds) and then decreases towards the convergence value (emission).

Pattern B: the value of the electric current increases to the value of convergence without achieving a negative value and the occurrence of an outburst.

Pattern C: the electric current value temporarily takes a value with a minus sign immediately after the start of the test (up to 2000 seconds) and then changes to a value with a plus sign and increases to a convergence value.

As a result, the circuit current IB converges most early with pattern B in FIG. 8. That is, with pattern B, the circuit current IB reaches the convergence value approximately 10,000 seconds after the start of the test. In contrast, with pattern A and pattern C, the current IB of the circuit is still far from the convergence value, even approximately 14000 seconds after the start of the test. Thus, the accuracy of setting the initial output voltage VSI affects the time of convergence of the current IB of the circuit. Accordingly, it is desirable to set the initial output voltage of the VSI with high accuracy.

Procedures for fine-tuning the initial VSI output voltage will be described. In the present embodiment, the initial output voltage VSI is set in accordance with the following procedures.

1. Measurement of the original battery voltage VB1

2. Temporary adjustment of the initial output voltage VSI

3. Measurement of current IB circuit

4. Fine adjustment of the initial VSI output voltage

5. Final Alignment of VSI Initial Output Voltage

The rest of this document describes the procedures in order. First, “procedure 1” refers to measuring the battery voltage VB at the time before testing the battery 1, i.e., the original battery voltage VB1. Measurement can usually be performed using a voltmeter. Voltmeter 6 in FIG. 1 may be separate from the DC power source 4 and may be used to measure, or other voltmeters may be used.

"Procedure 2" refers to adjusting the output voltage VS of the DC power source 4 in FIG. 1. The adjustment is performed so that the VS output voltage coincides with the original battery voltage VB1, measured in "Procedure 1". This is how the initial VSI output voltage is set, although the adjustment made at this point in time is a time setting. This is because the measurement accuracy of the original battery voltage VB1, measured in “Procedure 1”, is not very high.

Next, current measurement is performed in "procedure 3". That is, the battery 1 is connected to circuit 3 in FIG. 1 is in a state where the initial output voltage of the VSI is temporarily set in "procedure 2". Then, the reading value of the ammeter 5 is measured at this time, i.e., the circuit current IB. Here, when the initial output voltage VSI, which is temporarily set in "procedure 2", coincides with the true initial voltage VB1 of the battery 1, the current must not flow into circuit 3. That is, the measurement value of the current IB of the circuit must be zero. However, a certain amount of current IB circuit can be observed in reality due to the problem of measurement accuracy in "procedure 1". When the temporarily given initial output voltage VSI is excessively high than the true initial battery voltage VB1, the measurement value with a plus sign is obtained as the current IB of the circuit. When the temporarily given initial output voltage VSI is excessively low, the measurement value with the minus sign is obtained.

Next, fine adjustments are made to the initial VSI output voltage. This corresponds to "procedure 4". Adjustment is performed by fine-tuning the output voltage VS of the DC power source 4 while viewing the value of the ammeter 5. As the current measurement can be performed with higher accuracy than the voltage measurement, the accuracy of the initial output voltage VSI can be increased by fine-tuning. Of course, the purpose of adjustment is to adjust the value of the reading of the ammeter 5 to zero. When a measurement value with a plus sign is provided in "procedure 3", fine adjustment is performed to lower the output voltage VS. When a measurement value with a minus sign is provided, a fine adjustment is performed to increase the output voltage VS. When a measurement value of zero is obtained during "procedure 3", adjustment is not necessary.

Thus, the VS output voltage after fine adjustment is finally matched as the final initial VSI output voltage (procedure 5). Then, a test is started by the measuring device 2. When the test is performed in this way, the test can be performed in this way when the circuit current IB converges early, as illustrated in pattern B in FIG. eight.

Meanwhile, when the measurement value with a plus sign is provided in “procedure 3”, and the verification starts without adjustment, the verification proceeds in a manner that implies a burst, which is illustrated as pattern A in FIG. 8. When the test starts without adjustment from the state of the measurement value with a minus sign, the test passes with a pattern implying a reverse current period, which is illustrated as pattern C in FIG. 8. When the output voltage VS increases after the start of the test, as in the aforementioned “characteristic moment 1”, in particular, divergence and oscillation can occur in the IB circuit current if the accuracy of the initial output voltage VSI is poor. Performing a fine adjustment of "procedure 4" can prevent this situation and provides an opportunity to conduct quality checks in a short time.

Characteristic moment 3 in the present embodiment: Setting the initial output voltage of the VSI to high

Next, a description is given of setting the initial VSI output voltage to a high voltage value. In the description so far, the initial value of the output voltage is set so that the reading value of the ammeter 5 becomes zero, i.e., the reading value coincides with the original battery voltage VB1. However, a value other than the original battery voltage VB1 can be set as the initial output voltage of the VSI. More specifically, the initial output voltage VSI can be set to a value higher than the original battery voltage VB1. It also helps to reduce the processing time required for the determination. This point will be described below.

First, the resistance Rp of a short-circuited circuit of the battery 1 illustrated in FIG. 1. As described previously, the resistance of a short-circuited circuit Rp is modeled after the smallest metallic foreign substance in the multilayer material 20 of the electrode. Even a non-defective rechargeable battery 1, which does not contain metallic foreign matter, still has a slight, but some amount of self-discharge. The actual amount of self-discharge in the battery 1 is the sum of the amount of self-discharge, still present even in the case of a non-defective battery, and the amount of self-discharge from the smallest metallic foreign substance. When the resistance of the self-discharge path, still present even in the case of a non-defective battery, is defined as the natural resistance Rp0 of the short-circuited circuit, and the resistance of the route of conducting electricity generated by the smallest metallic foreign substance, is defined as the resistance Rp1 of the short-circuited foreign substance, the above-mentioned resistance Rp of the short-circuited is parallel combined resistance for the natural resistance of the Rp0 short-circuited circuit and Determination of the Rp1 short-circuited chain of a foreign substance in reality. Therefore, the battery 1 still contains a self-discharge current determined from the battery voltage VB and the natural resistance of the short-circuited Rp0 even when the battery 1 is non-defective. A defective battery 1 contains an even higher self-discharge current due to the presence of the resistance Rp1 of a short-circuited foreign substance.

Therefore, when the output voltage VS of the DC power source 4 is determined to neutralize the self-discharge current corresponding to the natural resistance Rp0 of the short-circuited circuit in the circuit in FIG. 1, the self-discharge current does not flow in a non-defective battery, and the battery voltage VB remains constant. In this case, the circuit current IB remains unchanged and constant. Even when the output voltage VS is determined in this way, the self-discharge current corresponding to the impedance Rp1 of the short-circuited foreign substance still passes if the battery 1 is defective, which results in a drop in the battery voltage VB. Accordingly, the self-discharge current increases. Therefore, the determination of quality can be performed in a shorter time compared with the case where the output voltage VS is the same as the original battery voltage VB1, as previously described.

A description is provided of how to determine the initial output voltage of the VSI when tested with measuring device 2 for suppression. First, the self-discharge current ID0 in the case of a non-defective battery is provided by the following expression (7):

ID0 = VB / Rp0 (7)

The self-discharge current ID0 can be suppressed when the IB circuit current provided by the aforementioned expression (1) matches the self-discharge current ID0 in expression (7). Therefore, the following expression is established:

(VS - VB) / Rx = VB / Rp0

When the above expression changes so that the output voltage VS is resolved, the initial output voltage VSI is obtained. In such a case, the above-mentioned initial battery voltage VB1 is used as the battery voltage VB. Therefore, the initial output voltage VSI is provided by the following expression (8):

VSI = VB1 * {1+ (Rx / Rp0)} (8)

Here, the natural resistance Rp0 of a short-circuited circuit is determined almost by the design of the battery 1. Therefore, the natural resistance Rp0 of a short-circuited circuit can be treated as a known value depending on the specification of the battery 1. The method for measuring the parasitic resistance Rx is as described previously. Therefore, since the right side of expression (8) includes only known values, the initial output voltage VSI can be determined. The initial output voltage VSI, defined in this way, is higher by "VB1 * (Rx / Rp0) of the original battery voltage VB1. Thus, starting a test with a high initial output voltage VSI allows the IB current to converge early.

The self-discharge current ID0, when the battery voltage VB is set as the initial battery voltage VB1 in the above expression (7), is the initial self-discharge current in the non-defective battery 1. When this self-discharge current ID0 is set as the standard IDI self-discharge current, (8) can be expressed as the following expression (9) using the standard IDI self-discharge current. Since the standard IDI self-discharge current is determined by the natural resistance of the short-circuited Rp0, which is the design value, and the initial battery voltage VB1 and the parasitic resistance Rx, which are the measurement values, the initial output voltage VSI can be calculated by the expression (9):

VSI = VB1 + (IDI * Rx) (9)

In this case, if the circuit current IB passes as a constant value without increasing even after the start of the test, the battery 1 in this case can be determined as non-defective based on the above description. When the circuit current IB increases after the start of the test, the battery 1 is defective in this case. The passage of circuit current IB is illustrated in FIG. 9. Therefore, the quality determination can be performed without waiting for the convergence of the current IB of the circuit. That is, a determination value of about 3-5 μA can be set as an increase limit in the IB circuit current, and quality can be determined based on whether or not the increase limit in the IB circuit current is equal or higher definitions. The determination time can be set to 20-30 minutes after the start of the test.

In the present embodiment, it is desirable to measure the circuit current IB, provided that the temperature of the battery 1 is constant relative to the temperature at the time point when the initial battery voltage VB1 is measured. When the temperature of the battery 1 changes in the middle of the test, the battery voltage VB and the circuit current IB are also affected by the change. Accordingly, since the change can also affect the determination of convergence and increase in the current IB of the circuit, this effect is eliminated.

Therefore, it is desirable to repeatedly obtain the temperature of the battery 1, before measuring the initial battery voltage VB1, in the middle of the measurement and in the middle of the subsequent measurement of the IB current, in parallel with the process of these measurements. The check only continues when the fluctuation in the resulting temperature is within the specified acceptable range of oscillation. With such a configuration, only when the temperature fluctuation of the battery 1 remains within an acceptable range of oscillation, can the verification be continued.

As described in detail above, according to the present embodiment, the presence or absence of the internal short-circuited circuit of the battery 1 is checked based on the current measurement instead of the voltage measurement. Here, an increase in the output voltage VS of the power source after the start of the test provides the possibility of earlier checking the battery 1. In addition, the formation of the surge and the period of the reverse direction of the circuit current IB are prevented by precisely matching the initial output voltage VSI of the power source with the original battery voltage VB1. Since the initial output voltage VSI of the power source is specifically set higher than the original battery voltage VB1 in order to suppress the self-discharge current ID0 when the battery 1 is non-defective, it becomes possible to perform a check based only on the presence or absence of an increase in the IB circuit current. Thus, the present embodiment implements the method of testing the battery 1, which can quickly determine the quality of the battery 1, regardless of changes in different conditions. The production method of the battery 1, which produces the battery 1, while at the same time performing such a test as a single process, is also realized.

The present invention is illustrative in all respects and is not considered a basis for restrictive interpretation. Therefore, the present invention can naturally perform various modifications and improvements without departing from the scope of the present invention. For example, in the description of the embodiment, it was described that the output voltage VS increases with a voltage that is equal to the original battery voltage VB1. It was also described that the initial voltage VSI of the output voltage VS is specifically set above the initial voltage VB1 of the battery. Based on the above description, a verification method may also be devised as a modification of the present invention. In this method, the initial value VSI of the output voltage VS is set to a value that is still higher than the output voltage VS after the convergence of the circuit current IB, and then, while the output voltage VS decreases with the passage of time, the convergence time of the circuit current IB is obtained. That is, the direction of the current IB of the circuit passing into the circuit 3 at the stage of applying the current is not limited to the direction of charge of the battery 1, but may be the direction of discharge of the battery 1.

Even when the initial value VSI of the output voltage VS is specifically set above the initial voltage VB1 of the battery, it is advisable to precisely set the output voltage VS at the stage when the output voltage VS used as the basis for tuning coincides with the initial voltage VB1 of the battery. The verification method of this embodiment can be performed not only for batteries directly after manufacturing as new products, but also for used batteries for purposes such as recovering used assembled batteries, for example. Electrical storage devices that need to be defined are not limited to batteries, but may be capacitors, such as electric double layer capacitors and lithium ion capacitors.

Claims (22)

1. The method of checking the electrical storage device, in which: make up a circuit with a rechargeable electrical storage device and a power source and transmit current through the power source to the circuit in the charging direction of the electrical storage device or in the discharge direction of the electrical storage device, the output voltage of the power source changing from the initial value with the passage of time; and when current passes, the quality of the electrical storage device is determined based on the state of convergence of the current passing through the circuit. 2. The test method according to claim 1, in which the initial value is additionally set to the voltage value before the start of the test of the charged electrical storage device, wherein with the passage of current, the output voltage after the start of the test changes so that the output voltage increases so that the limit of the increase in the output voltage increases more when the increase in the current after the start of the test becomes larger, and in determining the quality of an electrical storage device, the quality of the electrical storage device is determined based on the time required until the current converges. 3. The test method according to claim 2, in which the output voltage is calculated using a constant, which is the product of the parasitic resistance value of the circuit and a predetermined positive coefficient, which is less than one, as the sum of the voltage of the electrical storage device and the product of the circuit current value and constant. 4. The test method according to claim 2, in which the output voltage is calculated using the virtual resistance value as the sum of the voltage of the electrical storage device and the product of the circuit current value and the sum of the parasitic circuit resistance value and the virtual resistance value, the virtual resistance value is used when the output voltage increases is replaced by a model where the absolute value of the virtual resistance, which is a virtual resistance that has a negative or well evoe resistance value, instead of increasing the output voltage, which is set constant. 5. The method of verification according to any one of paragraphs. 1-4, in which additionally: before drawing up the circuit, a voltage value is obtained before the start of testing a rechargeable electrical storage device; before passing the current, the output voltage is matched with the voltage value; and determine the initial output voltage of the power source during the passage of current by adjusting the output voltage so that the current passing through the circuit is suppressed after the output voltage coincides with the voltage value. 6. The verification method according to claim 1, wherein with the passage of current, the voltage of the power source at the beginning of the test is set to the value obtained by adding the product of the initial self-discharge current of the electrical storage device without a defect and the parasitic resistance of the circuit with the voltage of the electric storage device, and when determining the quality of the electrical storage device, the quality of the electrical storage device is determined based on whether or not the increase in current is at a predetermined level after the start of the test. 7. The method of verification according to any one of paragraphs. 2-4, in which the passage of current, the voltage of the power source at the beginning of the test is set to the value obtained by adding to the specified or determined value of the voltage of the product of the initial self-discharge current of the electrical storage device without a defect and the parasitic resistance of the circuit. 8. The method of verification according to any one of paragraphs. 1-4, in which the voltage value is additionally measured before the test of a rechargeable electrical storage device, while measuring the voltage value and the passage of current are performed under the condition that the electrical storage device has a constant temperature. 9. The test method according to claim 8, wherein additionally before measuring the voltage value and in the middle of measuring the voltage value and passing the current, the temperature is repeatedly obtained in parallel with the measurement of the voltage value and passing the current and continue to measure the voltage value and pass the current when the resulting temperature fluctuation is in a predetermined acceptable range of oscillation. 10. The method of verification according to any one of paragraphs. 1-4, in which the voltage value is additionally measured before testing a rechargeable electrical storage device, while the electrical storage device has the appearance of a flat square shape, and the measurement of the voltage value and current transmission is performed under the condition that the electrical storage device is under increased pressure the direction of the thickness of the electrical storage device. 11. A method for producing an electrical storage device in which: performing an initial charge of an assembled and uncharged electrical storage device to a predetermined charged state in order to provide a chargeable electrical storage device; and check the rechargeable electric storage device by the verification method according to any one of claims. 1-4.

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